payloads/ext/ Fix SeaBIOS race condition

For a very long time, SeaBIOS sometimes failed to build when using
multiple threads. This known problem has been haunting everyone for a
very long time. Until now.

Unlike most other payloads, building SeaBIOS results in two files: the
SeaBIOS payload itself and SeaVGABIOS. Each file has its own target, and
there's a third target called "seabios", which has the same recipe as
the SeaBIOS file, which calls `payloads/external/SeaBIOS/Makefile` with
a bunch of arguments. In addition, SeaVGABIOS depends on "seabios".

When executing serially, if the file of either SeaBIOS or SeaVGABIOS is
needed, the SeaBIOS Makefile will be run. This will generate both files,
so it is not necessary to run the Makefile more than once.

However, when using multiple threads, it can happen that one thread
wants to make the SeaBIOS file, while another one wants to make the
SeaVGABIOS file, which depends on "seabios". This implies that both
threads will execute the SeaBIOS Makefile at about the same time, only
to collide when performing git operations. Since git uses a lock file
when updating the index, one of the threads will fail to acquire the
lock with an error, which will ultimately cause the build to fail.

Whenever this happened, manually aborting with Ctrl-C made the build
process fail again because of the same error. The only way to get past
this problem, other than using one thread, was to let the unfinished
jobs complete. The thread that acquired the lock on the SeaBIOS git
repository would finish building SeaBIOS, so that target would not need
to be remade. When restarting the build, only the target that failed is
rebuilt, so it does not collide with any other thread.

To address this issue, make the SeaVGABIOS file target depend directly
on the SeaBIOS file instead, and remove the duplicate "seabios" target.

Change-Id: I251190d3bb27052ff474f3cd1a45022dab6fac31
Signed-off-by: Angel Pons <>
Tested-by: build bot (Jenkins) <>
Reviewed-by: Arthur Heymans <>
Reviewed-by: Nico Huber <>
1 file changed
tree: 95b51bc876e3e6d5049bbffe479712b8eccc7bba
  1. 3rdparty/
  2. configs/
  3. Documentation/
  5. payloads/
  6. src/
  7. util/
  8. .checkpatch.conf
  9. .clang-format
  10. .editorconfig
  11. .gitignore
  12. .gitmodules
  13. .gitreview
  16. gnat.adc
  18. Makefile

coreboot README

coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload.

With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required.

coreboot was formerly known as LinuxBIOS.


After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.

See for a list of supported payloads.

Supported Hardware

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

Build Requirements

  • make
  • gcc / g++ Because Linux distribution compilers tend to use lots of patches. coreboot does lots of "unusual" things in its build system, some of which break due to those patches, sometimes by gcc aborting, sometimes - and that's worse - by generating broken object code. Two options: use our toolchain (eg. make crosstools-i386) or enable the ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case).
  • iasl (for targets with ACPI support)
  • pkg-config
  • libssl-dev (openssl)


  • doxygen (for generating/viewing documentation)
  • gdb (for better debugging facilities on some targets)
  • ncurses (for make menuconfig and make nconfig)
  • flex and bison (for regenerating parsers)

Building coreboot

Please consult for details.

Testing coreboot Without Modifying Your Hardware

If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU.

Please see for details.

Website and Mailing List

Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website:

You can contact us directly on the coreboot mailing list:

Copyright and License

The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.